Problems with the Mirror modifier
I can see that the pivot point you are talking about, is not at the center of the mesh.
The Pivot point is the orange dot with a black outline.

To center the pivot point, go to into Object mode, select the car mesh, right click, Set Origin -> Origin to Geometry.
Then the pivot point should be centered.

Also, try deselect the Bisect for the X axis in the modifier options.

Let me hear if it worked :)